1. Field of the Invention
The present invention relates to an image output apparatus, and more particularly to an image output apparatus for outputting a three-dimensional image.
2. Description of the Related Art
A method known as the multi-view three-dimensional picture display method is given in U.S. Pat. No. 3,895,867 in which pictures are taken with a camera using a photographic film which will accept a plurality of images which are shifted with respect to each other only by the parallax in perspective between a pair of views. The negative imprinted on this film is then used to make a combined image by going from a plurality of points via a lenticular lens. This image is then printed. If this printed image is then viewed via the same lenticular lens, an image which appears to be three-dimensional can then be viewed without the aid of glasses.
Also, a method for obtaining a three-dimensional image has been proposed in Japanese Patent Application Laid-Open No. Hei 2-87792 in which a plurality of television images picked up by using a plurality of television cameras are synthesized and displayed on a display of the television set and the synthesized image is observed through a lenticular lens provided on the display field surface.
Furthermore, a method is put forward where an item such as a lenticular lens made up from a large number of rows of semi-cylindrical lenses is used. When a large number of images arranged along a first direction are then viewed, only one of these images is selected to be expanded from its compressed size for viewing so that a three-dimensional visual effect results. This kind of display method is put forward in, for example, in Television Association Magazine Vol. 45, No. 11, pp. 1472 to 1474 (1991) entitled 50-inch multi-vision three-dimensional television without glasses.
In the image arrangement for carrying out the aforementioned display method, for example, n cameras are used to pick up images of the target (object) from different perspectives. When each of the images obtained by these n cameras are composed, n pixels will correspond to one pitch p, the width of the lens taken along the direction at right angles to the generating line for a single semi-cylindrical lens, of the lenticular lens, and just one of these n pixels will correspond to each of the n cameras. As only one of the n pixels within a single pitch p will correspond to one of the n cameras, (n-1) of the frames taken by each camera can be discarded, i.e. (n-1) pixels are cancelled out.
By arranging the pixels and projecting the synthesized image onto a screen made of a diffusion plate and a lenticular lens in accordance with this method, when viewing is carried out via the lenticular lens, just one pixel will be selected for display from the n pixels within a single pitch for a single perspective, i.e. one view. It follows that as different perspectives are displayed for two-view, i.e. two perspectives, displays such as three dimensional displays become possible.
The aforementioned thinning out of the composite pixel arrangement for the n images will be described using FIG. 11. FIG. 11a is an outline cut-away view of one part of lenticular lens sheet 120 made up of an arrangement of lenticular lenses consisting of a plurality of semi-cylindrical lenses 101, 102, 103, . . . placed on the front surface of a light diffusion type display board 110 for displaying, for example, n images to be described in the following. Also, FIG. 11c shows each of the pixels and their rows for the images taken by the plurality of cameras. In the example in FIG. 11 there are four cameras, 131 to 134, with pixels A11, A12, . . . A36 for camera 131, pixels B11, B12, . . . B36 for camera 132, pixels C11, C12, . . . C36 for camera 133 and pixels D11, D12, . . . for camera 134. FIG. 11b then shows the arrangement of each of the pixels for images displayed within a single pitch of each of the semi-cylindrical lenses as viewed from below, from the display board side of the lenticular lens sheet 120 in FIG. 11a.
In FIGS. 11a to 11c, for example, the only pixels which are selected for displaying from within one pitch of the semi-cylindrical lens 101 are the column of A11, A21, A31, . . . pixels from camera 131, the column of B12, B22, B31, . . . pixels from camera 132, the column of C13, C23, C33, . . . pixels from camera 133 and the column of D14, D24, D34, . . . pixels from camera 134. These are then displayed in columns at the display board 110 as is shown in FIG. 11b. Also, the only pixels which are selected for displaying from within one pitch of the semi-cylindrical lens 102 are the column of A15, A25, A35, . . . pixels from camera 131, the column of B16, B26, B36, . . . pixels from camera 132, the column of C17, C27, C37, . . . pixels from camera 133 and the column of D18, D28, D38, . . . pixels from camera 134. These are then displayed in columns at the display board 110 as is shown in FIG. 11b. Predetermined columns of pixel data from each of the respective pixels from cameras 131 to 134 in FIG. 11c are then also selected from within a pitch of the semi-cylindrical lens 103 to be displayed in rows at the display board 110.
In this way, images from each of the plurality (four) of cameras 131 to 134 are now displayed at the display board 110 of the lenticular lens sheet 120. If these images displayed on the display board 110 are then viewed via each of the semi-cylindrical lenses 101, 102, 103, . . . , it is possible to see different images for each of the different perspectives LA to LD. For instance, an image photographed by camera 131 can be viewed at perspective LA, an image photographed by camera 132 can be viewed at perspective LB, an image photographed by camera 133 can be viewed at perspective LC and an image photographed by camera 134 can be viewed at perspective LD.
Also, thinning out is carried out for each of the pixels when images from each of the cameras 131 to 134 are displayed at the display board 110. For example, A12, A22, A32, . . . , A13, A23, A33, . . . , A14, A24, A34, . . . , A16, A26, A36, . . . from each of the images taken by camera 131 in FIG. 11, B11, B21, B31, . . . , B13, B23, B33, . . . , B14, B24, B34, . . . , B15, B25, B35, . . . from each of the images taken by camera 132, C12, C22, C32, . . . , C13, C23, C33, . . , C14, C24, C34, . . . , C15, C25, C35, . . . , C16, C26, C36, . . . from each of the images taken by camera 133 and D11, D21, D31, . . . , D12, D22, D32, . . . , D13, D23, D33f . . . , D15, D25, D35, . . . , D16, D26, D36, . . . from each of the images taken by camera 134 are all cancelled.
When the cancellation is effected, the image is enlarged in a direction which is at right angles to the direction of the generating lines for each of the semi-cylindrical lenses 101, 102, 103, . . . shown in FIG. 11 which make up the lenticular lens. By using a lenticular lens sheet having these kinds of characteristics, an image having a height to width ratio of 1:1 can be obtained as for a normal display apparatus.
A three-dimensional display apparatus employing a method for structuring more detailed images where the pixels are arranged in rows is described in Laid-open publication Hei 3-97390. According to the apparatus in this publication, in the same way as the aforementioned literature, 50-inch multi-vision three-dimensional television not requiring glasses, pixel data for n source images are gathered in 1/n parcels by cancelling out to get a source size image. However, in addition to this, cancelling out is carried out and n differing pixels are lined up every one pitch in the horizontal direction, i.e. in a direction perpendicular to that of the generating lines for the lenticular lens. The same pixels are then repeatedly lined up n times in the lengthwise direction of the lenticular lens, i.e. the direction of the generating lines, so as to give a method with an n.times.n image size.
A description will now be given using FIGS. 12a to 12c of the pixel arrangement when an n.times.n image size is obtained by repeatedly displaying pixels n times along the lengthwise direction of the lenticular lens. Here, FIG. 12a is a cut-away outline of the surface of one part of the same lenticular lens sheet 120. As in FIG. 11a, FIG. 12c, in the same way as FIG. 11c, is a view of each of the pixels and rows for the images taken by, for example, the four cameras 131 to 134. FIG. 12b shows the arrangement, i.e. the arrangement when viewed from the lower surface of the lenticular lens sheet 120, of each of the pixels to give an n.times.n image size.
In FIG. 12, for example, each of the pixels displayed from within one pitch p of the semi-cylindrical lens 101 are, as is shown in FIG. 12b, the pixel column A11, A21, A31, . . . , the column B11, B21, B31, . . . , the column C11, C21, C31, . . . , and the column D11, D21, D31, . . . which have been selected from the pixels in FIG. 12c coming from the cameras 131 to 134. Also, for the case in FIG. 12, these pixels are repeated in groups of n (which in this case is 4) along the direction of the generating lines (i.e. the longitudinal direction) of the respective semi-cylindrical lenses. For instance, the column A11, A11, A11, A11, A21, A21, A21, A21, A31, A31, . . . , the column B11, B11, B11, B11, B21, B21, B21, B21, B31, B31, . . . , the column C11, C11, C11, C11, C21, C21, C21, C21, C31, C31, . . . and the column D11, D11, D11, D11, D21, D21, D21, D21, D31, D31, . . . , are arranged along the generating line direction within a pitch p of the semi-cylindrical lens 101. In the same way, the column A12, A12, A12, A12, A22, A22, A22, A22, A32, A32, . . . , the column B12, B12, B12, B12, B22, B22, B22, B22, B32, B32, . . . , the column C12, C12, C12, C12, C22, C22, C22, C22, C32, C32, . . . and the column D12, D12, D12, D12, D22, D22, D22, D22, D32, D32, . . . , are arranged within a pitch p of the semi-cylindrical lens 102 and the column A13, A13, A13, A13, A23, A23, A23, A23, A33, A33, . . . , the column B13, B13, B13, B13, B23, B23, B23, B23, B33, B33, . . . , the column C13, C13, C13, C13, C23, C23, C23, C23, C33, C33, . . . and the column D13, D13, D13, D13, D23, D23, D23, D23, D33, D33, . . . , are arranged within a pitch p of the semi-cylindrical lens 103.
In this way, if these images displayed on the display board 110 are then viewed via each of the semi-cylindrical lenses 101, 102, 103, . . . , it is possible to see different images for each of the different perspectives LA to LD. Also, the same pixels are lined up in rows of four along the generating line direction of the image for the semi-cylindrical lens and by also enlarging the image in a direction which is parallel to the generating line direction, in this case by four times, an image which is 4.times.4 larger can be viewed.
Accordingly, it may be possible to view an image which differs depending on the perspective by picking out just one pixel of images taken by a plurality of cameras for each pitch of p of the lenticular lenses in the kind of lenticular lens sheet 120 shown in FIGS. 11a to 11c. However, as it is intended to carry out corrections on the enlargement of the picture in the direction which is at right angles to the angle of the generating lines for each of the semi-cylindrical lenses, the pixels have to be cancelled, which causes the picture quality to be inferior when compared to usual display apparatus.
Also, with the kind of display board 120 shown in FIGS. 12a to 12c, the pixels are repeatedly displayed n times along the longitudinal direction of the lenticular lenses so as to give an n.times.n image size. However, in this case, the image size becomes large when compared with that for normal display apparatus. The apparatus therefore has to be made large in order to display the entire image and the large volume of data is difficult to handle. It is also not possible to achieve a density which is high when compared with normal display apparatus.
On the other hand, in the method proposed in the above-described U.S. Pat. No. 3,895,867 where photographic pictures are taken with a camera onto a photographic film, a processing dark room is required for putting the images on film and a solid display cannot be displayed if the actual object is not photographed. Also, as the resolution now depends solely on the resolution of the light sensitive paper, the resolution of, for example, a high resolution print for a directional display cannot be improved. The image is also enlarged in a direction which is at right angles to the direction of the generating lines for the semi-cylindrical lenses so as to give the same resolution in the direction of the generating lines for the semi-cylindrical lenses and in the direction which is at right angles to the direction of the generating lines and this also causes deterioration in the picture quality.
Also, the methods explained in conjunction with FIGS. 11a to 11c and FIGS. 12a to 12c suffer from a disadvantage that a device for projecting the three-dimensional image onto the planar display board is always required for observing the 3D image although the method can obtain the 3D image in a real time fashion.